Geospatial contents and capabilities are increasingly available.
Different agencies have developed their own geospatial
catalogues to facilitate discovery, access, and sharing of
large volumes of geospatial data and processing capabilities.
But the discovery of multi-discipline geospatial content is
time-consuming and tedious, especially when the catalogues
use different metadata models and access protocols. To provide
a catalogue that presents a unique well-known metadata model
and interface protocol to users and hides the complexity and
diversity of the affiliated catalogues is very desirable [10]